I have an air and I can run cs5 and final cut pro at the same time with no problems.
DEFINITELY not saying not to get a pro though, I just didnt have the money for a 15"+ pro or else I would have. So my advice, Get a Pro if you have funding.
"Well I was over In Australia during Easter which was interesting... Interesting to know they celebrate the Holiday the same way we do: By commemorating the Death and resurrection of jesus by telling our children that a giant BUNNY RABBIT left them chocolate eggs in the night. Now... I wonder why we are fucked up as a race... " Bill Hicks